Prior Art Statement
U.S. Pat. No. 4,113,471 discloses a process for brine leaching oxide ores to non-selectively solubilize non-ferrous metal values as chlorides, at elevated temperatures and pressures with the addition of oxygen. Leaching is required for a time of 1/4 to 12 hours. There is no selective leaching of lead or silver chlorides from their sulfide ores.
U.S. Pat. Nos. 4,135,993 and 4,173,623 teach brine leaching lead chloride at temperatures of 80.degree.-120.degree. C. to selectively solubilize the lead chloride out of a sulfidic residue containing the sulfides of copper, iron and zinc as well as elemental sulfur. The leaching is not done under pressure. Leach times of 1/4 to 2 hours are required in both processes.
International publication No. WO 80/00852, class 22 B 13/00, published under the patent cooperation treaty on May 1, 1980 (01.05.80), discloses the recovery of lead from crystallized lead chloride by reduction with hydrogen or a hydrogen containing compound accompanied by condensing lead chloride volatilized during the reduction process.